Few horror films had such an impact on moviegoers as "Saw." The film did so well on its opening weekend that a sequel was approved almost instantly. However, the original film was only intended to be a one-off, and as such, a script had to be written entirely from scratch in order to continue the series. Even worse was the fact that director James Wan and screenwriter Leigh Whannell could not return for a sequel due to other commitments. "Saw" producer Gregg Hoffman did not have any ideas about who could direct the follow-up film, and it was only when he received a script for another film that he found his guy. Darren Lynn Bousman had just completed a script and was trying to sell it to film studios when it was decided his script would be a good fit for "Saw II."

Because Bousman's script had been intended for another film, changes had to be made in order to make it fit with the "Saw" franchise. Leigh Whannell was asked to edit the script, and he did so with input from original director Wan. The two of them were hired as executive producers, with most of the original crew members returning to shoot the sequel. "Saw II" received a production budget four times that of the first installment in the series. It was reported at the time that multiple endings were shot so as to not give away the ending to eager fans. While director Bousman had finalized a very tight script, he did allow the actors to improvise in certain situations if they felt it necessary to do so.

The opening scene of the film is very similar to the first, with a character trapped in a room trying to avoid death. A police informant is told to extract a key from behind his right eye so he can free himself; otherwise, a spike-filled mask will close around his head. The informant cannot carry out the action, and so he is killed.

While investigating the crime scene, police detective Eric Mathews (played by Donnie Wahlberg) follows the trail and leads a SWAT team to find John Kramer holed up in a factory. A computer monitor shows eight people trapped inside a house, one of whom is Eric's son. The eight are told that a nerve agent will soon fill the house, but there are antidotes hidden around the house. Several of the hostages are killed in the deadly house while searching for the antidote.

Back at the factory, John reveals that he had tried to take his own life after learning he had cancer, but he could not follow through. He then decided to create a situation where he could test others' will to live. At the house, one of the hostages, Xavier, realizes that the pin code to the safe holding the antidote can be found on the back of everyone's necks. He goes on a killing spree, and the others soon learn about the code. Eric holds a gun to John's head and forces him to take them to the house, where the carnage has long since ended. It is then revealed that video tapes were playing on the television, and the events in the house happened before the cops arrived. In the final scene, Eric is bound to pipes and left to die in a bathroom by one of John's many protégés.

"Saw II" was released in October of 2005, but not without some controversy. The original film poster had two bloodied and cut fingers, but the MPAA rejected it. The poster was instead used for the film's soundtrack cover. Film reviews were generally mixed, with many saying that it might not appeal to newcomers but would be loved by diehard fans of the original. Tobin Bell was praised for his performance as John Kramer, and he won the Best Villain Award at the Fangoria Chainsaw Awards.

"Saw II" opened with revenue of $31 million at the box office and ended up with a total of $147 million worldwide. In later years, there were a further five films made, but "Saw II" had the highest revenue of them all. After the production of "Saw 3D" in 2010, no further films have been made. However, Lionsgate is looking to release an eighth film and is unsure whether to continue the plot of the originals or to reboot the franchise. Nothing is set as of 2013, but "Saw" fans would be more than happy if the series continued in some form.